In communication systems and networks, error correction coding is often employed in order to increase the ability to recover the originally transmitted data in the presence of channel noise and related impairments. Forward error correction coding is one type of coding scheme that is commonly employed.
High speed data transmission systems such as dense wavelength division multiplexed (DWDM) interfaces employ coded transmissions with forward error correction (FEC). Both for performance management (e.g., alarming a signal degradation) and for reactive protection switching processes (e.g., signaling to fast reroute protocol engines), pre-FEC in-service signal quality indicators are useful.